Publisher's Synopsis
This report presents nearly all structural data available from explosion tests of 20-psi mine ventilation seals and concrete-block ventilation stoppings that were conducted by the National Institute for Occupational Safety and Health during 1997-2008. Although the seals tested were designed to meet the former federal 20-psi pressure design standard, the structural information contained herein on these seal tests will facilitate the analysis and design of coal mine seals that meet the new explosion pressure design criteria of 50 and 120 psi as set forth in the Mine Safety and Health Administration (MSHA)'s final rule on "Sealing of Abandoned Areas." The seal testing data are organized into six broad categories of seal structures based on the materials used and the construction method for those 20-psi seals: 1. Concrete like materials with steel reinforcement and reinforcement bar anchorage to rock; 2. Pumpable cementitious materials of varying compressive strengths with no steel reinforcement and no hitching; 3. Articulated structures such as solid-concrete-block seals and ventilation stoppings made of solid and hollow-core concrete blocks; 4. Polymer and aggregate materials without hitching; 5. Wood-crib-block seals with or without hitching; 6. Articulated structures such as lightweight blocks with or without hitching. This report organizes and presents the applied loading or P-t curves and, when available, the measured displacement-time (D-t) curves for 44 different seal structures tested prior to 2006 when the former 20-psi explosion pressure design criterion applied to mine seals. Also included in this data set are the applied loading P-t curves and response D-t curves for eight different ventilation stoppings constructed with solid or hollow-core concrete blocks. These structural test results against the stop-pings are included as supplemental information pertinent to the design of seals that incorporate concrete blocks in some capacity.
